Process of producing invisible writing



Patented Sept. 14, 1937 2,093,397

UNITED STATES PATENT OFFICE PROCESS OF PRODUCING INVISIBLE WRITING JohnWesley MeCulloch and Chester H. Myers, Monroe, Oreg.

No Drawing. Application March 1, 1937, Serial No. 128,547

2 Claims. (Cl. 41-20) Our invention relates generally to means forwriting indentations on the wet sheet entirely disproducing invisiblewriting on surfaces, and parappear. ticularly to a process of treating asheet of paper The resultant wet sheet which is no longer or the like toproduce invisible writing thereon, wet, can in this processed conditionbe either 5 which writing can be restored to visibility at will storedor mailed or otherwise handled.

and rendered again invisible, and an important When it is desired tocause the writing on the object of our invention is toprovide a processof Wet sheet to reappear, this wet sheet is placed this character whichis simple, efiicient, and me in a basin or trough of water, whereupon,after expensive and wherein a permanent record is elapse of a shorttime, the original writing on the available. wet sheet will becomevisible. 10

Other important objects of our invention will After the writing has beencaused to re-appear be apparent from a reading of the following deand hep rpo e f u h reapp r having scription taken in connection with theexample been Served, the Sheet can then h P given for illustrativepurposes, away to dry and the writing will disappear again.

The process of the present invention contem- Thereafter whenever it isdesired to cause the 5 plates the production of invisible but restorablewriting to become visible the wet sheet is placed Writing upon sheets ofordinary paper, so that the in water as described above. The productionof sheets may be utilized as and stored as perthe ppe e a d theproduction of the pmanent records in which the invisible writing maypearance of the writing may be repeated an inbe restored at any desiredfuture time and again definite number of times with the same wet 0rendered invisible. sheet.

The embodiment of the present invention con- Although we have shown anddescribed herein templates a process wherein an ordinary sheet of a p eed embodiment of the Process of 0111 white typewriting or other writingpaper is placed nve it iS to be definitely understood, that in a basinor trough containing water and per- We do not desire to limit theapplication of the 25 mitted to remain in the Water for about fivemininvention thereto, and any Change a e utes or until the same becomesthoroughly soaked y he a in the Sequence and du a on o and wet through,so as to produce what is herein- S eps a pe at s, Wit in the Spirit Ofthe inafter referred to as wet sheet. vention and the scope of thesubjoined claims.

This wet sheet is then placed on a glass or Having described theinvention what is claimed 30 other suitable smooth and polished surfaceof as new is!- non-absorbent character, and on this wet sheet A pr ofproducing invisible Writing n so imposed on the supporting surface, isplaced a sheet and restoring such writing to visibility, a dry sheet ofpaper similar in size and constitus d p oce s mp s ou y wettin id tionto the sheet from which the wet sheet is sheet, then pla thereS111tentWet Sheet on a 35 produced, and in substantial registry withthe support g ur ace and on the wet sheet then wet sheet. imposing a drysheet, then writing on said dry An ordinary lead pencil or othersuitable writs eet in a manner to indent Said ing stylus is then takenand used to write in the t e dry g S d We Sheet so as to cause the 4ordinary way on the dry sheet. When this writwriting to d app and thenWetting e dr d ing is completed, the dry sheet is removed and Wet sheetso as to cause the Writin to pp may be destroyed, since it is then of nofurther 2. A proce of producing invisible Writing o a use in theprocess. sheet and restoring such writing to visibility, said The wetsheet indented by the writing is then process comprising thoroughlywetting said 5 taken from the glass supporting surface and sheet, thenplacing the resultant wet sheet on 5 placed between two pieces of whiteabsorbent a supporting surface and on the wet sheet then cloth, such asordinary dish towels, so that a imposing a dry sheet, then writing onsaid dry goodly proportion of the superficial moisture in sheet in amanner to indent said wet sheet, then the wet sheet and on the surfacethereof is abdrying said wet sheet so as to cause the writ- 5 sorbed bycontact with the absorbent cloths. ing to disappear; and then wettingthe dried wet 5 After the wet sheet has been placed as desheet so as tocause the writing to appear, said scribed between the two pieces ofabsorbent cloth, drying being accomplished by ironing the wet theassembly is placed on a suitable supporting wet sheet between absorbentsheets until said surface and a medium hot sadiron or other equivwetsheet is dry and the Writing thereon has alent ironing instrument isapplied to the top disappeared. 55

cloth and the assembly ironed until the moisture JOHN WESLEY MCCULLOCH.in the wet sheet has been dissipated and the CHESTER I-I. MYERS.

